How to use Java operation to integrate the database of Graph, Document, Key/Value? Java 10-minute tutorial

Keywords: Javascript Attribute Java Database Eclipse

1
2 BaseDocument myObject = new BaseDocument();
3 myObject.setKey("myKey");
4 myObject.addAttribute("a", "Foo");
5 myObject.addAttribute("b", 42);
6 try {
7   arangoDB.db(dbName).collection(collectionName).insertDocument(myObject);
8   System.out.println("Document created");
9 } catch (ArangoDBException e) {
10  System.err.println("Failed to create document. " + e.getMessage());

The result should be:

1 Document created

Some details you should know about the code:

• setKey() Sets the key value of the new object

• addAttribute() places a new key / value pair in the object

• Each attribute is stored in the document root directory as a single key/value pair

Reading document

Read the created document:

  1
  2 try {
  3  BaseDocument myDocument = arangoDB.db(dbName).collection(collectionName).getDocument("myKey",
  4      BaseDocument.class);
  5  System.out.println("Key: " + myDocument.getKey());
  6  System.out.println("Attribute a: " + myDocument.getAttribute("a"));
  7  System.out.println("Attribute b: " + myDocument.getAttribute("b"));
  8 } catch (ArangoDBException e) {
  9   System.err.println("Failed to get document: myKey; " + e.getMessage());
   }

The result should be:

1
2 Key: myKey
3 Attribute a: Foo
  Attribute b: 42

Some details you should know about the code:

getDocument() returns stored document data to a given JavaBean (BaseDocument)

Read VelocyPack Format Documents

You can also read VelocyPack format documents:

1
2 try {
3   VPackSlice myDocument = arangoDB.db(dbName).collection(collectionName).getDocument("myKey",
4    VPackSlice.class);
5  System.out.println("Key: " + myDocument.get("_key").getAsString());
6  System.out.println("Attribute a: " + myDocument.get("a").getAsString());
7  System.out.println("Attribute b: " + myDocument.get("b").getAsInt());
8 } catch (ArangoDBException | VPackException e) {
9   System.err.println("Failed to get document: myKey; " + e.getMessage());
}

Some details you should know about the code:

Update document

1
2 myObject.addAttribute("c", "Bar");
3 try {
4  arangoDB.db(dbName).collection(collectionName).updateDocument("myKey", myObject);
5 } catch (ArangoDBException e) {
6  System.err.println("Failed to update document. " + e.getMessage());
}

Read the document again

Let's read the document again:

1
2 try {
3   BaseDocument myUpdatedDocument = arangoDB.db(dbName).collection(collectionName).getDocument("myKey",
4      BaseDocument.class);
5   System.out.println("Key: " + myUpdatedDocument.getKey());
6   System.out.println("Attribute a: " + myUpdatedDocument.getAttribute("a"));
7   System.out.println("Attribute b: " + myUpdatedDocument.getAttribute("b"));
8   System.out.println("Attribute c: " + myUpdatedDocument.getAttribute("c"));
9 } catch (ArangoDBException e) {
10  System.err.println("Failed to get document: myKey; " + e.getMessage());
  }

The result should be:

1
2 Key: myKey
3 Attribute a: Foo
4 Attribute b: 42
 Attribute c: Bar 

remove document

Let's delete a document:

1 
2 try {
3   arangoDB.db(dbName).collection(collectionName).deleteDocument("myKey");
4 } catch (ArangoDBException e) {
5   System.err.println("Failed to delete document. " + e.getMessage());
}

Execute AQL queries

First we need to create some documents named Homer in the collection first Collection:

1
2 ArangoCollection collection = arangoDB.db(dbName).collection(collectionName);
3 for (int i = 0; i < 10; i++) {
4   BaseDocument value = new BaseDocument();
5  value.setKey(String.valueOf(i));
6  value.addAttribute("name", "Homer");
7  collection.insertDocument(value);
 }

Get all documents named Homer from the collection first Collection and traverse the stored results:

 
try {
  String query = "FOR t IN firstCollection FILTER t.name == @name RETURN t";
  Map<String, Object> bindVars = new MapBuilder().put("name", "Homer").get();
  ArangoCursor<BaseDocument> cursor = arangoDB.db(dbName).query(query, bindVars, null,
      BaseDocument.class);
  cursor.forEachRemaining(aDocument -> {
    System.out.println("Key: " + aDocument.getKey());
  });
} catch (ArangoDBException e) {
  System.err.println("Failed to execute query. " + e.getMessage());
}

The result should be:

Key: 1
Key: 0
Key: 5
Key: 3
Key: 4
Key: 9
Key: 2
Key: 7
Key: 8
Key: 6 

Some details you should know about the code:

• AQL query syntax uses placeholder @name, which must be bound to a value

• query() executes the defined query and returns an ArangoCursor with a given class (here: BaseDocument)

• Sequence is not guaranteed

Delete documents using AQL

Now we will delete the document we created before:

try {
  String query = "FOR t IN firstCollection FILTER t.name == @name "
          + "REMOVE t IN firstCollection LET removed = OLD RETURN removed";
  Map<String, Object> bindVars = new MapBuilder().put("name", "Homer").get();
  ArangoCursor<BaseDocument> cursor = arangoDB.db(dbName).query(query, bindVars, null,
      BaseDocument.class);
  cursor.forEachRemaining(aDocument -> {
    System.out.println("Removed document " + aDocument.getKey());
  });
} catch (ArangoDBException e) {
  System.err.println("Failed to execute query. " + e.getMessage());
}

The result should be:

Removed document: 1
Removed document: 0
Removed document: 5
Removed document: 3
Removed document: 4
Removed document: 9
Removed document: 2
Removed document: 7
Removed document: 8
Removed document: 6

Learn more

• See AQL Documentation, further study our query language.

• Want to know more about our database? click here!

• Reading about Collections More information.

• Browse more about this in our documentation Documents Information.

• For more examples, you can browse ArangoDB recipe.